1Field of the Invention
The present invention relates to a process for producing a .beta.-lactone derivative which is useful as a starting material for polymers, an intermediate in the field of organic synthetic chemicals, a starting material for medicaments, and the like.
2Background Art
Conventionally, there are known the following processes for producing a .beta.-lactone derivative:
(1) a method described by H. E. Zaugg in Organic Reactions, Vol. 8, pp. 305-363 (1954) wherein ketene and an aldehyde are reacted in the presence of a Lewis acid catalyst such as a halide of boron, zinc, aluminum, titanium, or iron or an organic complex of the halide; PA1 (2) a method disclosed in Japanese Patent Publication (kokoku) No. 47-25065 wherein a ketene and an aliphatic aldehyde are reacted in the presence of tetrahydrofuran together with boron trifluoride and/or a complex thereof; PA1 (3) a method disclosed in Japanese Patent Application Laid-Open (kokai) Nos. 46-51422, 48-61420, and 48-64019 wherein a ketene and an aliphatic aldehyde are reacted in the presence of a boron trifluoride-ether complex as a catalyst; PA1 (4) a method disclosed in U.S. Pat. No. 2,763,644 wherein 4-methylene-2-oxetane, also called diketene, is hydrogenated in the presence of palladium black; PA1 (5) a method described by Y. Zhang et al. in Macromolecules, Vol. 23, pp. 3206-3212 (1990) wherein a hydroxyl group of a 3-hydroxycarboxylate ester is mesylated with methanesulfonyl chloride, the resultant ester is hydrolyzed, and the hydrolysate is cyclized with sodium hydrogencarbonate; PA1 (6) a method described by T. Sato et al. in Tetrahedron Lett., Vol. 21, pp. 3377-3380 (1980) wherein a 3-bromocarboxylic acid derivative is cyclized with sodium carbonate; and PA1 (7) a method described by W. Adam et al. in J. Am. Chem. Soc., Vol. 94, pp. 2000-2006 (1972) or described by T. H. Black et al. in J. Org. Chem., Vol. 53, pp. 5922-5927 (1988) wherein a .beta.-hydroxycarboxylic acid derivative is cyclized by the treatment with benzenesulfonyl chloride in the presence of pyridine.
However, processes for producing a .beta.-lactone derivative which have been reported so far are not satisfactory, and have problems described below.
For example, in the process (1), since catalysts do not necessarily show the same activity in various condensation reactions, a suitable catalyst must be selected in accordance with the target .beta.-lactone. The process (2) has limitation on reaction conditions such as a constant mol ratio of the aldehyde to ketene of 1.0/0.9 or constant reaction temperature of 10-15.degree. C. The process (3) provides poor yield of a .beta.-lactone derivative. The process (4) is not suited for producing a typical .beta.-lactone derivative, since the product is limited to 4-methyl-2-oxetanone. The processes (5) to (7) require intricate procedures for preparing starting materials.